1. Field of the Utilization
The present invention relates to an apparatus which adjusts the printing pressure of printing cylinders for the purpose of improving operation performance.
2. Description of the Prior Art
As a printing press for printing bank notes and other securities, a satellite-type printing press for simultaneous multicolor printing has been known. In this printing press, a plurality of plate cylinders are arranged in a satellite form around a single gathering rubber cylinder, and the multicolor printing is performed at the same time by applying the printing pressure while feeding printing paper in between an impression cylinder or a rubber blanket cylinder revolving in contact with the gathering rubber cylinder. The printing press of this type is capable of obtaining printed matter without miss-registering.
FIG. 5 schematically shows the constitution of the satellite-type printing press. On a frame 1 of a printing press body are supported a pair of rubber blanket cylinders 2. Around each of these rubber blanket cylinders 2 are mounted, in a satellite form, a plurality (four in the illustrated example) of plate cylinders 3, which revolve in contact with the rubber blanket cylinders 2. To each of the plate cylinders are connected a plurality of inking arrangements 4, which are mounted to a frame 5 of the inking arrangement unit. These inking arrangements 4 are designed to supply printing ink to the plate cylinders 3.
The sheet is fed from a sheet feeder into a pair of rubber blanket cylinders 3, and is fed out, after printing on both sides thereof, to a delivery apparatus not illustrated.
In the satellite-type printing press shown in FIG. 5, the printing pressure is adjusted so as to be constantly a fixed value by shifting the position of the rubber blanket cylinders 2 in the event that the sheet to be printed has change in thickness. However, when the position of the rubber cylinders 2 is shifted, the printing pressure of both the plate cylinders 3 and the rubber blanket cylinders 2 varies; it is therefore necessary to shift each of the plate cylinders in accordance with the amount of movement of the rubber blanket cylinders 2.
In the following, the movement mechanism of the plate cylinders 3 will be explained by referring to FIG. 6. The plate cylinders 3a and 3b are supported on both ends by eccentric bearings 4a and 4b, which are revolvably mounted on the frame. On the eccentric bearings 4a and 4b are rotatably mounted the plate cylinders 3a and 3b through bearings which are offset from the center of rotation C-1- of the eccentric bearings 4a and 4b. The center of rotation C-2- of the plate cylinders 3a and 3b has an offset position set so that, during the operation of the printing press, a straight line between the center of rotation C-2- of the plate cylinder 3a and 3b and the center of rotation C-1- of the eccentric bearings 4a and 4b will meet at right angles with the straight line between the center of rotation not illustrated of the rubber blanket cylinders 2 and the center of rotation C-1- of the eccentric bearings 4a and 4b.
With the rotation of the eccentric bearings 4a, and 4b in relation to the frame, the center of rotation C-2- of the plate cylinders 3a and 3b changes its position, turning around the center of rotation C-1- of the eccentric bearings 4a and 4b and accordingly enabling the retreat of the plate cylinders 3a and 3b from the rubber blanket cylinders 2 and printing pressure adjustment.
In the flange section of either of the eccentric bearings 4a and 4b, a sector gear 16 is fixedly mounted en bloc coaxially with the center of rotation of C-1- of the eccentric bearings 4a and 4b. The sector gear 16 is in mesh with a sector gear section 17 of a lever 18, which is integrally secured on either end of a connecting shaft 19 which is rotatably mounted through the frame. To the other end of the lever 18 of the connecting shaft 19, the top end section of a piston rod 21 of a fluid pressure cylinder 20a and 20b pivotally mounted on the frame is connected through a pin 22 to actuate the fluid pressure cylinders 20a and 20b. Thus the arm 18 rotates together with connecting shaft 19, turning the eccentric sleeves 4a and 4b through the sector gear section 17 and the sector gear 16. Eccentric cams 25a and 25b are mounted, facing to the forward end of the piston rods 21 of the fluid pressure cylinders 20a and 20b. These cams are formed integral with printing pressure adjusting shafts 24a and 24b supported on the frame in parallel with the center of rotation C-2- of the plate cylinders 3a and 3b and rotate in contact with the forward end of the piston rods 21, thereby restricting the end of stroke of the fluid pressure cylinder 20a and 20b in the direction of rotation of the plate cylinders 3a and 3b which rotate in contact with the rubber blanket cylinder 2.
That is, rotating the printing pressure adjusting shafts 24a and 24b changes the contact position between each piston rod 21 at one stroke end and the eccentric cams 25a and 25b, thus restricting the amount of rotation of the lever 18. Consequently the printing pressure of the plate cylinders 3a and 3b to be applied to the rubber blanket cylinders 2 can be changed.
In the above-described printing press when the rubber cylinder 2 is moved, the eccentric sleeve 4 is rotated to shift the plate cylinder 3 in accordance with the amount of movement of the rubber cylinder 2, thereby keeping a constant printing pressure of the plate cylinders 3 to be applied to the rubber cylinder 2. However, since four plate cylinders 3 are mounted in contact with one rubber cylinder 2, it is necessary to adjust all of the plate cylinders 3 respectively, and in addition the eccentric sleeves 4 must be adjusted on both the control side and the driving side. Therefore, when the sheet thickness of the printing paper has been changed, the adjustment of the eccentric sleeves 4 the same time in accordance with the amount of adjustment of the stop member by means of the interlock mechanism, and the amount of eccentricity of the second cylinder is changed to keep a constant printing pressure between the first and second cylinders.
The present invention and its features and advantages will be set forth and become more apparent in the detailed description of the preferred embodiment presented below, when read in connection with the accompanying drawings.